This invention concerns an improved process for preparing alkylene glycols and their alkyl ethers by reaction of oxides of carbon with hydrogen in presence of a catalyst system.
There are even-increasing efforts to provide new methods of making ethylene glycol particularly useful as a component in polyester fiber and antifreeze formulations. An ever present aim is to prepare said glycol in relatively high yields involving a catalyst system providing good selectivity.
One proposed mode of making ethylene glycol is the reaction of carbon monoxide and hydrogen in presence of variously proposed catalyst systems. The mixture of carbon monoxide and hydrogen, commonly known as synthesis gas, is reacted at elevated pressures and temperatures. For example, in Belgium patent No. 793,086 and U.S. Pat. No. 3,940,432 there is described the co-synthesis of methanol and ethylene glycol from mixtures of carbon monoxide and hydrogen using a complex rhodium catalyst. While other metals of group VIII of the Periodic Table have been tested for activity under similar conditions, including cobalt, ruthenium, copper, manganese, iridium and platinum, only cobalt was found to have slight activity. The use of ruthenium compounds in particular failed to produce polyfunctional products such as ethylene glycol. This is illustrated in U.S. Pat. No. 3,833,634 for solution of triruthenium dodecarbonyl.
This invention therefore is to provide a process of making alkylene glycols and their ethers utilizing a highly effective catalyst system which produces said glycols and ethers in good yields and selectivity. Advantageously with the catalyst system of this invention hydrocarbon formation during the course of the reaction is largely avoided and the catalyst system itself can be recycled to the process while maintaining a high degree of activity.